This invention relates generally to joining lengths of pipe and more particularly concerns methods, structure and apparatus for securing a sleeve to a pipe so as to create a pipe splice.
In lieu of welding lengths of pipe to form a pipe line, a method and apparatus for splicing pipe lengths using sleeves to overlap and join pipe length ends is disclosed in U.S. Pat. No. 4,327,471 entitled "Hydrostatic Pipe Splicing Method" and U.S. Pat. No. 4,330,918 entitled "Hydrostatic Pipe Splicing Apparatus", both assigned to the assignee of this application. This technique involves using a short, cylindrical sleeve to span abutted ends of pipe lengths, and then exerting very high propellant forces to drive the sleeve against the pipe beyond the elastic limit of the sleeve but within the elastic limit of the pipe. Upon dissipation of the propellant force, the pipe elastically returns and the pipe and sleeve are intimately joined.
A technically successful joint of this kind should ideally be stronger than the pipe itself in the sense of resisting longitudinal pull-out, and pull-out or separation as a result of bending the pipe line at the joint. In addition, a commercially successful joint of this kind should be designed to use sleeves and propellant force-creating charges of minimum size and cost, consistent with achieving the necessary technical standards.